Connection between deworming and miscarriage?

Producer Question from 2010

Q:  Bought a few cows at sale on Wed. Vet had them at 7 months breed. Brought them home and dewormed with Ivomec pour-on on Saturday. The next day one of the cows had miscarried. Is there a connection between deworming and miscarriage or was it going to happen anyway? (July 24, 2010)

A:  In regards to your question concerning the cow that miscarried, I would say that it was likely a result of the combination of her going through a sale, transport, and being worked. There is no known association between deworming with ivomec products and abortion. Many cows have been dewormed with this product, and products like this, at fall pregnancy checks without this adverse effect.

While it is unfortunate that this cow lost her calf, we do expect a small percentage (~3%) of pregnant cows to lose their calves as a normal occurrence.

Dr. Richard RandleRichard F. Randle, DVM
Extension Beef Cattle Veterinarian
Department of Veterinary & Biomedical Sciences
University of Nebraska–Lincoln